CN114361449B - Carbon nanotube coated FeF 3 Is synthesized by the method of (2) - Google Patents
Carbon nanotube coated FeF 3 Is synthesized by the method of (2) Download PDFInfo
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- CN114361449B CN114361449B CN202210081992.XA CN202210081992A CN114361449B CN 114361449 B CN114361449 B CN 114361449B CN 202210081992 A CN202210081992 A CN 202210081992A CN 114361449 B CN114361449 B CN 114361449B
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- 229910021393 carbon nanotube Inorganic materials 0.000 title claims abstract description 81
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 74
- 239000002041 carbon nanotube Substances 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title abstract description 26
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 19
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 14
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 9
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims abstract description 9
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 9
- 238000001308 synthesis method Methods 0.000 claims abstract description 9
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000005011 phenolic resin Substances 0.000 claims abstract description 8
- 229920001568 phenolic resin Polymers 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 7
- 239000008098 formaldehyde solution Substances 0.000 claims abstract description 7
- 239000000725 suspension Substances 0.000 claims abstract description 7
- 239000002994 raw material Substances 0.000 claims abstract description 6
- 239000007788 liquid Substances 0.000 claims abstract description 5
- 238000000926 separation method Methods 0.000 claims abstract description 5
- 238000005406 washing Methods 0.000 claims abstract description 5
- 239000007791 liquid phase Substances 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 238000003763 carbonization Methods 0.000 claims description 10
- 239000007789 gas Substances 0.000 claims description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 9
- 229910002588 FeOOH Inorganic materials 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000012298 atmosphere Substances 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000000576 coating method Methods 0.000 claims description 8
- 229960004887 ferric hydroxide Drugs 0.000 claims description 8
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims description 8
- 238000010907 mechanical stirring Methods 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 239000011261 inert gas Substances 0.000 claims description 7
- 230000009467 reduction Effects 0.000 claims description 6
- 239000012071 phase Substances 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- CUPCBVUMRUSXIU-UHFFFAOYSA-N [Fe].OOO Chemical compound [Fe].OOO CUPCBVUMRUSXIU-UHFFFAOYSA-N 0.000 claims description 3
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 239000012299 nitrogen atmosphere Substances 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 19
- 230000008569 process Effects 0.000 abstract description 18
- 239000003792 electrolyte Substances 0.000 abstract description 6
- 238000007086 side reaction Methods 0.000 abstract description 5
- 239000007774 positive electrode material Substances 0.000 abstract description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 abstract 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 abstract 2
- 238000010000 carbonizing Methods 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 description 10
- 229910015475 FeF 2 Inorganic materials 0.000 description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 238000009396 hybridization Methods 0.000 description 5
- 239000003054 catalyst Substances 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 239000002073 nanorod Substances 0.000 description 4
- 238000000197 pyrolysis Methods 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 239000013543 active substance Substances 0.000 description 3
- -1 californium metals Chemical class 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 239000004917 carbon fiber Substances 0.000 description 3
- 238000010891 electric arc Methods 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- KTWOOEGAPBSYNW-UHFFFAOYSA-N ferrocene Chemical compound [Fe+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 KTWOOEGAPBSYNW-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- DGXAGETVRDOQFP-UHFFFAOYSA-N 2,6-dihydroxybenzaldehyde Chemical compound OC1=CC=CC(O)=C1C=O DGXAGETVRDOQFP-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 150000001721 carbon Chemical group 0.000 description 2
- 238000007036 catalytic synthesis reaction Methods 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000004071 soot Substances 0.000 description 2
- 238000002604 ultrasonography Methods 0.000 description 2
- 229910052686 Californium Inorganic materials 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910017855 NH 4 F Inorganic materials 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- HUFIRBOBXZUFPV-UHFFFAOYSA-N benzene-1,3-diol Chemical compound OC1=CC=CC(O)=C1.OC1=CC=CC(O)=C1 HUFIRBOBXZUFPV-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- CREMABGTGYGIQB-UHFFFAOYSA-N carbon carbon Chemical compound C.C CREMABGTGYGIQB-UHFFFAOYSA-N 0.000 description 1
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 1
- 239000002134 carbon nanofiber Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 230000021615 conjugation Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000011267 electrode slurry Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- SHXXPRJOPFJRHA-UHFFFAOYSA-K iron(iii) fluoride Chemical compound F[Fe](F)F SHXXPRJOPFJRHA-UHFFFAOYSA-K 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910001512 metal fluoride Inorganic materials 0.000 description 1
- 239000002082 metal nanoparticle Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000002048 multi walled nanotube Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 239000002109 single walled nanotube Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000010189 synthetic method Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a carbon nano tube coated FeF 3 The synthesis method of (2) comprises the following steps: s1, taking ferric oxide hydroxide, cetyl trimethyl ammonium bromide, resorcinol, formaldehyde solution and ammonia water as raw materials, reacting in a liquid phase, and carrying out solid-liquid separation, washing and drying on the obtained suspension to obtain phenolic resin coated ferric oxide hydroxide; s2, carbonizing to obtain Fe 3 O 4 An @ CNT; the Fe obtained is 3 O 4 Reducing the @ CNT to obtain Fe @ CNT; s3, carrying out fluorination to obtain the carbon nano tube coated FeF 3 . The invention can synthesize the carbon nano tube coated FeF with excellent structure and performance and good consistency 3 The material effectively solves the problems of the prior FeF 3 As the positive electrode material has poor conductivity, is easy to generate side reaction with electrolyte, has the problems of volume expansion, volume shrinkage and the like in the charge and discharge process, and has the advantages of low cost, simple process, easy realization and the like.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery materials, and in particular relates to a carbon nano tube coated FeF 3 Is a synthetic method of (a).
Background
Carbon Nanotubes (CNT) were found in the production of Carbon fibers from an arc process using a high resolution transmission electron microscope by physicist rice island clarifying men in the wave NEC laboratory of japan, month 1, 1991. It is a tubular carbon molecule, each carbon atom on the tube adopts sp 2 The hybridization is combined with each other by carbon-carbon sigma bonds to form a honeycomb structure consisting of hexagons as a skeleton of the carbon nano tube. A pair of p electrons on each carbon atom that do not participate in hybridization form a conjugated pi electron cloud with each other across the entire carbon nanotube. According to the number of layers of the tube, it is divided into single-wall carbon nanotubes and multi-wall carbon nanotubes. The tubes being very thin in the radial direction, only on the nano-scale, and axiallyIt can be as long as tens to hundreds of microns.
Due to the adoption of sp by carbon atoms in the carbon nanotubes 2 Hybridization compared to sp 3 Hybridization, sp 2 The s orbit component ratio in the hybridization is larger, so that the carbon nano tube has high modulus and high strength. In addition, the melting point of the carbon nanotubes is expected to be as high as 3652-3697 ℃.
The p-electrons of carbon atoms on carbon nanotubes form a wide range of delocalized pi bonds, and carbon nanotubes have some special electrical properties due to the remarkable conjugation effect.
The synthesis of carbon nanotubes mainly includes two methods: one is a direct current arc discharge evaporation synthesis method (DC Arc discharge Evaporation Mothed, hereinafter referred to as DAEM), and the other is a Catalytic synthesis method (CM).
Direct current arc discharge evaporation synthesis (DAEM): the preparation of carbon nanotubes by DAEM is carried out in a graphite rod arc reactor, which is very similar to the Haufler-Ktolo synthesis apparatus. In a cylindrical vessel of the reactor, two graphite rods were placed at an anode and a cathode, respectively, to serve as electrodes, which were 1-2 cm apart. The vessel was filled with an inert gas He or Ar at a pressure of 53kPa. Then, a direct current with a large current value is introduced to make the arc temperature reach more than 3000 ℃, and soot is generated at the cathode. After the reaction was completed, the soot was dispersed with toluene or ethanol by means of an ultrasonic cleaner to obtain a suspended sample.
Catalytic synthesis (CM): CM refers to the synthesis of carbon nanotubes from organic matter by pyrolysis under the action of a catalyst. This is very similar to vapor grown carbon fibers. Catalysts fall into two classes, the first class being transition metals such as Fe, co, ni and Cu, and the second class being californium metals, principally Gd, nd, la and Y. And M.endo et al use iron as a catalyst and benzene as a precursor, and synthesize the carbon nanotubes by using a device for preparing vapor-phase grown carbon fibers.
The metal fluoride has higher specific capacity as the positive electrode, is hopefully applied to the lithium ion battery with high energy density, but is currently in the laboratory research stage because of low electronic conductivity, low ionic conductivity and volume expansion in the charge and discharge process.
For lithium ion battery materials, the carbon nano tube has the function of bearing high internal stress, the one-dimensional shape of the carbon nano tube is effectively maintained in the lithium ion deintercalation process, the existence of the carbon nano tube also improves the conductivity of the electrode material, and the carbon nano tube has good electrical contact with conductive carbon black, so that the carbon nano tube is a novel nano structure of an electrode active substance (core)/carbon nano tube (shell) structure. 2014 entitled "CarbonNanotubeEncapsulated FeF 2 Nanorods for HighPerformance Lithium-Ion Cathode Materials "proposes the use of ferrocene and NH 4 Preparation of FeF directly from F as raw material 2 CNT, 2.5mmol of ferrocene and 10mmolNH 4 F, grinding uniformly in an agate mortar, putting the mixture into a 30mL autoclave, heating the autoclave to 500 ℃ at a speed of 5 ℃/min, and preserving heat for 3 hours to carry out pyrolysis reaction. Cooling to room temperature after the reaction to obtain FeF 2 @CNT, feF is washed with deionized water and acetone 2 And (5) drying the@CNT to obtain a product. Production of FeF 2 The process of @ CNT is shown in FIG. 1, where first, ferrocene will decompose into iron and carbon atoms, and then iron will react with NH 4 F production of FeF 2 Nanorods, feF 2 Acting as a catalyst in the growth of the carbon shell. With increasing temperature and time, a C shell is first formed, and then FeF 2 Filling into carbon nano tube to form semi-closed FeF 2 @cnt. However, this method can only produce FeF 2 @cnt composite material, iron fluoride FeF 2 The theoretical specific capacity is 570mAh/g, the specific capacity of the material is only 200mAh/g at 500mA/g (0.87C), the energy density is relatively low when the material is used for a lithium ion battery, and the cost of raw materials required by the method is high.
FeF 3 The theoretical specific capacity of the material is higher, and at present, feF is also compounded by adopting carbon coating or carbon nano tube in the prior art 3 Modification of materials, but with carbon-coated FeF 3 The material has small contact area due to gaps among particles, and the conductivity of the material is improved as compared with that of the carbon nano tubes crosslinked with each other; while the carbon nano tube composite material can better improve the conductivity, feF 3 Attached to carbon nanotubesOn the electrolyte and exposed FeF 3 The direct contact causes side reactions, which in turn lead to poor recycling properties of the material.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a synthetic carbon nano tube coated FeF 3 Effectively solves the problems of the prior FeF 3 The carbon nano tube coated FeF which is used as the positive electrode material has poor conductivity and is easy to generate side reaction with electrolyte, has the problems of volume expansion, volume shrinkage and the like in the charge and discharge process, and has excellent structure and performance can be synthesized 3 The material has the advantages of low cost, simple process, easy realization, good consistency of the prepared material, good performance and the like.
In order to solve the problems, the applicant has found through analysis that by preparing the carbon nanotube coated FeF 3 The material can effectively overcome the problems, however, the applicant finds that the prior art is difficult to synthesize the carbon nano tube coated FeF through analysis 3 Material, especially carbon nano tube coated FeF with good coating effect 3 A material.
In order to achieve the above object and solve the above technical problems, the present invention provides the following technical solutions through a great deal of research:
carbon nanotube coated FeF 3 The synthesis method of (2) comprises the following steps:
s1, taking ferric hydroxide, hexadecyl trimethyl ammonium bromide, resorcinol and formaldehyde solution as raw materials, adding ammonia water to adjust the pH value, reacting in a liquid phase to obtain suspension, and carrying out solid-liquid separation, washing and drying on the obtained suspension to obtain the phenolic resin coated FeOOH;
s2, coating the obtained phenolic resin with FeOOH for carbonization to obtain Fe 3 O 4 An @ CNT; the Fe obtained is 3 O 4 Reducing the @ CNT to obtain Fe @ CNT;
s3, carrying out fluorination on the obtained Fe@CNT to obtain the carbon nanotube coated FeF 3 。
Preferably, in step S2, the carbonization is performed under an inert atmosphere or nitrogen, and the reduction is performed under an inert atmosphere or nitrogen and H 2 Is carried out under a mixed atmosphere of (2).
Preferably, the carbonization and reduction conditions are: firstly, raising the temperature to 600-630 ℃ at 1-10 ℃/min (more preferably 1-5 ℃/min, still more preferably 1-3 ℃/min) under nitrogen or inert atmosphere, preserving heat for 2-4 h, raising the temperature to 650-680 ℃ at 1-10 ℃/min (more preferably 1-5 ℃/min, still more preferably 1-3 ℃/min), and preserving heat for 2-4 h under the condition of introducing nitrogen or mixed gas of inert gas and hydrogen. The inventor finds that the resorcinol-formaldehyde resin is carbonized into a porous C shell and H after analysis in the process 2 The reaction can only be carried out in the shell through the gaps and reacts with the nuclei, but the process is slower, and the problems of incomplete reaction, uneven nucleation and the like caused by rapid temperature rise can be avoided by controlling a preferable temperature mechanism to effectively improve the uniformity of nucleation and the completeness of the reaction. In the nitrogen gas or the mixed gas of the inert gas and the hydrogen gas, the volume concentration of the hydrogen gas may be, for example, preferably 5 to 15%.
Preferably, the step S1 specifically includes: firstly dispersing ferric hydroxide in water, then adding hexadecyl trimethyl ammonium bromide, resorcinol and ethanol under ultrasonic and mechanical stirring, continuing ultrasonic mechanical stirring, then adding ammonia water and formaldehyde solution, keeping ultrasonic mechanical stirring, carrying out reaction, and carrying out solid-liquid separation, washing and drying on the obtained suspension to obtain the phenolic resin coated FeOOH.
Preferably, the molar ratio of the ferric hydroxide to the resorcinol is 1:5-1:8; the molar ratio of the iron oxyhydroxide to the formaldehyde is 1:8-1:10; the mass ratio of the ferric hydroxide to the cetyltrimethylammonium bromide is 1:4-1:10. The inventor finds that a great amount of C, H organic gas can be generated in the carbonization pyrolysis process by controlling the molar ratio of FeOOH to resorcinol to be 1:5-1:8, and the carbon nano tube can be self-grown into the carbon nano tube under the condition of keeping cladding under the catalysis of Fe ions, otherwise, the carbon nano tube cannot be generated and a spindle type C shell can be generated.
Preferably, in step S3, the fluorination is gas phase fluorination; the gas phase fluorination is: heating the obtained Fe@CNT to 280-300 ℃, and introducing NF 3 The temperature is kept for 2 to 3 hours. By optimizing the gas phase fluorination temperature, excessive NF temperature can be avoided 3 Will oxidize the C shell to CF 4 However, too low a temperature may result in incomplete fluorination. NF (NF) 3 Can be NF 3 Mixed gas with nitrogen or inert gas, wherein NF 3 The volume concentration may be 5-15%.
Preferably, the temperature rising rate of the fluorination process is 3 to 5 ℃/min.
Preferably, the ammonia water is added in an amount to maintain the pH of the reaction system at 8 to 10.
Compared with the prior art, the invention has the following beneficial effects:
1. the preparation method of the invention can synthesize CNT (carbon fiber) to FeF (FeF) 3 FeF with good coating 3 On the basis of poor conductivity and poor dynamics of fluoride, the presence of the CNT in the@CNT composite material improves the conductivity, and the nano-scale inner core can effectively alleviate the defect of poor dynamics. FeF synthesized by the invention 3 CNT composite material capable of improving conductivity of material and preventing FeF 3 Directly produces side reaction with electrolyte and provides enough space for FeF in the charge and discharge process 3 The volume expansion and contraction are carried out, the cracking of the carbon shell caused by the expansion or contraction of the material is avoided, and the inner core is exposed to react with the electrolyte; the raw materials adopted by the method are cheap and easy to obtain, the cost is low, the preparation method is simple and easy to realize, and the controllability is strong.
2. Compared with FeF prepared by hydrothermal method 2 Crushing the morphology of the@CNT, breaking the inner core out of the shell, and having poor uniformity and FeF 2 The theoretical capacity of the @ CNT is only 570mAh/g, and the specific capacity of the @ CNT is only 200mAh/g at the multiplying power of 0.87C; feF prepared by the invention 3 The @ CNT composite material has uniform shape and size, no cracking phenomenon of the CNT, and the obtained FeF 3 The core is smaller in volume, more kinetically advantageous, and FeF 3 The @ CNT can realize the theoretical specific capacity of 713 mAh/g, and the specific capacity of 450mAh/g is still remained after 1000 circles of circulation under the multiplying power of 1.0C, so that the practicability is greatly improved.
Drawings
FIG. 1 shows a prior art FeF preparation 2 Schematic of the formation process of CNT nanorods.
FIG. 2 shows a synthetic carbon nanotube coated FeF according to the present invention 3 Is a schematic of the formation process.
FIG. 3 is a prior art FeF preparation 2 SEM image of CNT nanorods.
FIG. 4 shows a carbon nanotube-coated FeF synthesized according to the present invention 3 SEM images of (a).
FIG. 5 carbon nanotube-coated FeF synthesized according to the present invention 3 And (3) a cycle chart of the assembled battery.
Detailed Description
The invention will be described more fully hereinafter with reference to the accompanying drawings and examples, in which the invention is shown, to facilitate understanding of the invention, but the scope of the invention is not limited to the specific examples below.
Example 1:
carbon nanotube coated FeF 3 The synthesis method of (2) comprises the following steps:
(1) Coating: dispersing 120mg of ferric hydroxide (FeOOH) in 120mL of deionized water, mechanically stirring under ultrasound for 10min, adding 600mg of cetyltrimethylammonium bromide (CTAB), 1000mg of Resorcinol (Resorcinol) and 30mL of ethanol, continuing ultrasonic mechanical stirring for 10min, and finally adding 500 μl of ammonia (NH) 3 ·H 2 O) and 1000. Mu.L of Formaldehyde solution (Formaldehyde), wherein the mass concentration of the Formaldehyde solution is 37%, the mass concentration of ammonia water is 25%, and the mechanical stirring is maintained for 1h under ultrasound. The resulting dispersion was centrifuged, washed 3 times with water and alcohol, and dried in a vacuum oven at 60℃for 6 hours.
(2) Carbonization and reduction: placing the dried FeOOH@RF into a boat, heating to 600deg.C at room temperature at a heating rate of 1.5 ℃/min, maintaining at 600deg.C for 2 hr, heating to 680 deg.C at 1.5 ℃/min, and introducing 5% (volume concentration) H 2 And (3) preserving heat for 2 hours under the condition of/Ar, and cooling to room temperature along with the furnace.
(3) Fluorination; the Fe@CNT obtained was warmed from room temperature to 280℃at 5℃per minute and then subjected to 5% NF 3 The temperature is kept for 2 hours under the condition of being cooled to room temperature along with the furnace.
And (3) battery assembly: the obtained active substance FeF 3 Mixing and grinding the CNT, the conductive agent Super P and the binder polyvinylidene fluoride (pvdf) according to the ratio of 8:1:1 respectively, adding N-methyl pyrrolidone (NMP) to prepare positive electrode slurry, drying, coating, and punching (phi=12 mm). The button cell was then assembled and tested for electrochemical performance.
The invention utilizes sufficient resorcinol and formaldehyde to react in alkaline environment regulated by ammonia water to form phenolic resin which is uniformly coated outside hydroxyl ferric oxide particles, and finally obtains the product FeF through carbonization, reduction and fluorination processes 3 The @ CNT, in which the carbonization process, resorcinol-formaldehyde resin pyrolysis, produced a large amount of C, H-containing gas, which was catalyzed by Fe to produce carbon nanotube shells in situ. As shown in FIG. 4, the Scanning Electron Microscope (SEM) shows that the uniformity and dispersibility of the carbon nanotubes are good, and FeF is shown in the SEM 3 The inner core is uniformly coated in the carbon nano tube, and the size of the inner core is 80-100 nm.
The electrochemical performance of the button cell assembled by the positive electrode material is shown in figure 5, and the electrochemical performance of the button cell assembled by the positive electrode material is shown in the figure, so that the prepared material has excellent electrochemical performance, the specific capacity of 660mAh/g is still remained after 500 circles of the button cell is circulated at 0.2C multiplying power, the specific capacity of 570mAh/g is still remained after 900 circles of the button cell is circulated at 0.5C multiplying power, the specific capacity of 450mAh/g is still remained after 1000 circles of the button cell is circulated at 1.0C multiplying power, the multiplying power performance is good, compared with the prior art, the specific capacity is improved by times, and more than 1000 circles of stable charge and discharge can be maintained.
Analysis in combination with fig. 4 and 5 shows that the active material FeF in nano-scale 3 The method is favorable for improving the kinetics of the reaction, the reaction is quicker and more sufficient, the coulomb efficiency in the charge-discharge cycle can reach more than 99.5 percent, the carbon nanotubes are mutually interwoven and associated to form a conductive network, the conductivity of the material is improved, and the coating of the carbon nanotubes and the FeF are realized 3 The side reaction of the electrolyte in direct contact is slowed down, which is beneficial to improving the charge and discharge capacity. The specific capacity of the assembled battery prepared in this example tended to rise gradually, especially at smaller rates, presumably (1) FeF 3 In charge-discharge cycle, li + ContinuouslyDuring the embedding and removing process, feF 3 The decomposition volume of the active substances continuously becomes smaller, and the reaction is more thorough when the oxidation-reduction reaction speed is slower; (2) the pseudocapacitive interface lithium storage generated by the catalytic action of metal nanoparticles on the surface of the negative electrode (nano Fe generated during cycling and reaching the negative electrode) on the decomposition of surface Solid Electrolyte (SEI) is the basis for increasing specific capacity.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (9)
1. Carbon nanotube coated FeF 3 Is characterized by comprising the following steps:
s1, taking ferric hydroxide, hexadecyl trimethyl ammonium bromide, resorcinol and formaldehyde solution as raw materials, adding ammonia water to adjust the pH value, reacting in a liquid phase to obtain suspension, and carrying out solid-liquid separation, washing and drying on the obtained suspension to obtain the phenolic resin coated FeOOH;
s2, coating the obtained phenolic resin with FeOOH for carbonization to obtain Fe 3 O 4 An @ CNT; the Fe obtained is 3 O 4 Reducing the @ CNT to obtain Fe @ CNT;
s3, carrying out fluorination on the obtained Fe@CNT to obtain the carbon nanotube coated FeF 3 。
2. The carbon nanotube-coated FeF of claim 1 3 Characterized in that in step S2, the carbonization is performed under an inert gas atmosphere or a nitrogen atmosphere, and the reduction is performed under an inert gas atmosphere or nitrogen and H 2 Is carried out under a mixed atmosphere of (2).
3. The carbon nanotube-coated FeF of claim 2 3 Characterized in that the carbonization and reduction conditions are: firstly, raising the temperature to 600-630 ℃ at 1-10 ℃/min under nitrogen or inert atmosphere, preserving heat for 2-4 h,heating to 650-680 deg.c at 1-10 deg.c/min and maintaining the temperature for 2-4 hr while introducing nitrogen or the mixture of inert gas and hydrogen.
4. The carbon nanotube-coated FeF of claim 1 3 The synthesis method of (1) is characterized in that the step S1 specifically comprises the following steps: first
Dispersing ferric hydroxide in water, adding cetyl trimethyl ammonium bromide, resorcinol and ethanol under ultrasonic and mechanical stirring, continuing ultrasonic mechanical stirring, adding ammonia water and formaldehyde solution, maintaining ultrasonic mechanical stirring, reacting, and carrying out solid-liquid separation, washing and drying on the obtained suspension to obtain the phenolic resin coated FeOOH.
5. The carbon nanotube-coated FeF of claim 1 3 The synthesis method is characterized in that the mol ratio of the iron oxyhydroxide to the resorcinol is 1:5-1:8; the molar ratio of the iron oxyhydroxide to the formaldehyde is 1:8-1:10; the mass ratio of the ferric hydroxide to the cetyltrimethylammonium bromide is 1:4-1:10.
6. The carbon nanotube-coated FeF of claim 1 3 Wherein in step S3, the fluorination is gas phase fluorination; the gas phase fluorination is: heating the obtained Fe@CNT to 280-300 ℃, and introducing NF 3 The temperature is kept for 2 to 3 hours.
7. The carbon nanotube-coated FeF of claim 6 3 The synthesis method of (2) is characterized in that the heating rate is 3-5 ℃/min.
8. The carbon nanotube-coated FeF of claim 3 3 The synthesis method is characterized in that the heating rate to 600-630 ℃ is 1-5 ℃/min; the temperature rising speed of the temperature rising to 650-680 ℃ is 1-5 ℃/min.
9. As claimed in claim 1The carbon nano tube is coated with FeF 3 The synthesis method is characterized in that the addition amount of the ammonia water is used for maintaining the pH value of a reaction system to be 8-10.
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